Molecular studies on the New Zealand tree ferns : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Palmerston North, New Zealand
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Date
2001
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Massey University
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Abstract
Molecular phylogenetic studies have been performed on the New Zealand tree fern
genera Alsophila, Dicksonia and Sphaeropteris, using DNA sequencing techniques
and Amplified Fragment Length Polymorphism (AFLP). Three DNA sequence
markers were used, two chloroplast: rbcL, trnL-trnF spacer, and one nuclear: 188.
Using a combination of rbcL sequences obtained in this study and previously
published sequences from GenBank an overall phylogeny for the tree fern clade is
proposed. This phylogeny suggests that the currently recognised families may need
revision. Phylogenetic analysis of molecular markers in Dicksonia suggests a three
way genetic split within the genus, which corresponds, to three observed spore
morphologies. AFLP studies on populations of Dicksonia lanata, which possesses
two distinct growth forms, shows evidence of a weak genetic split, although probably
not sufficient to warrant the separation of two species. Studies on the Cyatheaceae
genera Alsophila and Sphaeropteris have confirmed observations on the evolution of
the New Zealand species based on morphology, and have also suggested a heretofore
unknown relationship between the South American fern genus Hymenophyllopsis and
the Cyatheaceae.
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Keywords
Dicksoniaceae, Cyatheaceae, Genetics Dicksoniaceae, Phylogeny Cyatheaceae, Evolutionary genetics